It can only be done by Groundspeak and they must accept your reason for "unactivation". Simple "unactivation" because you want to have more valuable coins will not help.
CZ: Většinou to povolili při chybné aktivaci mince, která nebyla v rukou člověka, který aktivoval.
I have activated almost all geocoins in my collection. Those that remain unactived all have the (ugly) generic icon. I like reading the Discovered logs after events. However, sometimes people just copy and paste an identical text which is not very encouraging. But I still feel people like seeing the collection.
As someone wrote earlier. There are activated (NOT circulated) coins I really want and I am willing to pay more just because I want them. For me as a buyer activation is not crucial.
In fact, there are only two coins snapped from both sides. On the left, the Dutch 2011 Geocoin by www.phdcoins.ca, and on the right, Bayern Geocoin 1.0 by www.mygeocoin.de.
November update of my seeking list
Celtic Three Dog Night Geocoin
Major League Geocoin
Leader of the Cache Geocoin (www.thecachingplace.com)
ET Highway II Geocoin (waiting for delivery, which is taking rather long)
MOGA 2011 Award Geocoin
or any other two-inch round geocoin with a unique icon that you cannot find in my list of owned trackables in my profile
My list of traders